Apparatus of the type having prime movers which require cooling are well known. Such apparatus would include various types of transportation vehicles, tractors and other agricultural equipment and implements, excavating equipment, and turf maintenance machines. Typically, the prime mover would be an internal combustion engine which could be selectively coupled to traction drive wheels and perhaps also to powered tools, either mechanically or through a hydraulic system. The present invention generally involves cooling systems for such apparatus. The invention will be described solely in terms of turf maintenance machines, but those skilled in the art will recognize that the invention is applicable to a wide variety of machines and implements.
Turf maintenance machines, particularly relatively large commercial machines, generally include a frame; a prime mover mounted on the frame, typically fore-and-aft; wheels supporting the frame, some or all of which are selectively coupleable through a transmission to the prime mover; a power take-off (PTO) extending from one end of the prime mover; a radiator adjacent the other end of the prime mover; and various tools, e.g., turf cutting units, operatively connectable to the PTO, often through a hydraulic system. If a hydraulic system is indeed used to power the working tools, a hydraulic fluid cooler or radiator can be mounted on the frame adjacent to the main (prime mover) radiator.
As is well known, vehicles such as automobiles typically include a cooling system which includes has a radiator for exchanging heat between a liquid coolant and the ambient air; a water pump for causing the coolant to flow between the prime mover and the radiator; and a thermostat for allowing fluid communication between the radiator and the prime mover when necessary. While a liquid coolant cooling system is useful in transportation vehicles, such a system is absolutely necessary for turf maintenance equipment wherein the prime mover drives the traction wheels, and also supplies power to the working tool(s), often through a hydraulic system. Some turf maintenance machines have tools which derive their power from frictional engagement with the ground as the traction vehicle traverses same. Other maintenance machines include tools which are directly powered by the prime mover independent of the traction wheels. In either case, waste heat must be dissipated into air passing through a radiator. However, as those skilled in the art of turf maintenance equipment recognize, the environment in which turf maintenance equipment must function renders this task difficult: grass clippings in particular tend to clog radiators and flow passages associated therewith. This being the case, turf maintenance equipment manufacturers usually recommend that equipment operators periodically check the radiator and/or radiator covers or screens to insure that minute air passageways are open.
Some manufacturers also include warning lights and/or temperature gauges which are designed to warn of overheating problems and signal the operator to remove grass clippings from the radiator and associated passageways.
As noted above, the prime mover of a typical piece of turf maintenance equipment has a PTO at one end and a radiator (and perhaps a hydraulic fluid heat exchanger) adjacent at the other end. Given this arrangement, various design configurations have been implemented. Referring to the attached Drawings, FIGS. 1-4 show, somewhat diagrammatically, various design configurations for turf maintenance equipment. In particular, FIG. 1 illustrates a fairly standard tractor pulling a gang of hydraulically-powered mowing reels. The reels are coupled, mechanically or hydraulically, to a PTO extending from the rearward end of the prime mover. A radiator is located at the front of the traction vehicle with a fan situated between the prime mover and the radiator suitable for drawing ambient air through the radiator. Of course, one or more drive wheels of the traction vehicle are also coupled to the prime mover through a transmission.
While the configuration illustrated in FIG. 1 is quite satisfactory for some applications, it is often preferable to locate the working tools toward the front of the vehicle. One popular form of turf maintenance equipment is a gang mower, wherein several lawn mowing units, e.g., reels, are held in spaced positions in transverse rows of one or more units so that their swaths overlap and so that the units are individually free to adapt themselves to the undulations of the ground. Gang lawn mower can include, for example, three or five mowing units disposed in two transverse rows. It is useful to have the cutting units adjacent to or in front of the operator so that he can easily observe the units and readily judge and control the degree of lap of the cuts of the outside units of the gang with the previous cut, and so that he can always see when any unit is not properly operating, whatever the reason.
In view of the desirability of having the cutting units forward of the operator, several alternative configurations have been suggested. One such configuration is shown diagrammatically in FIG. 2. In this design, the radiator is again located at the forwardmost end of the traction vehicle and the PTO faces the rear of the vehicle. However, in this case the working tools are located forward of the radiator and are coupled to the PTO through a lengthy mechanical or hydraulic system. Due to the distance between the PTO and the working tools, fairly high mechanical or hydraulic losses can result. Moreover, grass clippings thrown upward by the cutting units and entrained by the cooling air can collect on the radiator or the screen covering the radiator. Thus, the operator is often put to the inconvenience of having to stop the traction vehicle simply to remove grass clippings from the radiator screen. Due to the inconvenience of this maintenance operation, many operators will tend to wait until the temperature warning light indicates that the prime mover is overheating. If the warning light should cease to function or function intermittently, overheating can damage the prime mover or associated components.
Thus, still another configuration has been tried, and FIG. 3 illustrates this third design. Here, the radiator is located toward the rearward end of the traction vehicle and the PTO is located near the front end of the vehicle. With this design, there is a shorter distance between the PTO and the cutting units, which of course is advantageous. Also, since the radiator is farther away from the cutting units, one might assume that it should not as readily plug with grass clippings. However, the rear-mounted radiators of such units do indeed tend to quickly plug with grass clippings, presumably because the grass clippings are churned upward by the rear wheels of the traction vehicle or perhaps simply because clippings are thrown upward and over the top of the traction vehicle by the cutting units themselves. Some manufacturers have mitigated the plugging problems associated with this design by elevating the air inlet to a more clipping-free area. While this technique tends to create less clipping blockage, the radiator screen is still located toward the back of the machine, an area often ignored by the operator: since the working units (e.g., reels) and controls are situated toward the front of the vehicle, operators will often forget to check the radiator or radiator screen for plugging problems.
Given these problems, still another confiquration has been offered. FIG. 4 shows this configuration. Here, the cutting units are located toward the front of the traction vehicle and the PTO is located toward the rear of the vehicle. Hydraulics are conveniently used to couple the PTO and the cutting units. An important feature of this design is that the radiator and the intake for same are located immediately behind the operator. Experience has shown that this area is often the cleanest area of the entire machine, i.e., and the area least likely to be subjected to airborne grass clippings. Also, the operator can very easily check, on a regular basis, to determine whether the intake screen has plugged, and if it has, can easily remove the grass clippings from the screen. Such a turf maintenance machine is sold by The Toro Company, assignee herein, under the designation GROUNDSMASTER 72.RTM.. Since the radiator is situated in a substantially grass-free area, it is less likely to plug; if plugging occurs or is imminent, the operator simply reaches over and wipes the grass clippings off the screen without stopping the cutting operation. While this design is therefore excellent in many respects, it still places the PTO quite some distance from the cutting units, resulting in unnecessary hydraulic losses and expense. Further, this design places the radiator fan immediately behind the operator. The sound level associated with such fans can be quite objectionable, particularly at close range. In fact, some European nations have stringent noise regulations which might totally preclude the use of this design.
The present invention addresses the problems associated with the cooling systems of prior art turf maintenance equipment (and other equipment, machines and implements having prime movers). In particular, the present invention includes a method and apparatus for cooling a prime mover which allows the PTO and the cooling air inlet to be on the same end of the prime mover. Thus, the cooling air inlet can be adjacent and behind the operator's seat (in a substantially clipping-free area); the PTO can be positioned acceptably close to the working tools; and the working tools can be located toward the front of the vehicle for ready observation by the operator.